Method of refining aromatic extract oils with barium compounds



acids.

United States Patent METHOD OF REFINING AROMATIC EXTRACT OILS WITH BARIUM COMPOUNDS Weldon G. Annable, Mundelein, and Robert M. Haines, Crystal Lake, 111., assignors to The Pure Oil Company, Chicago, 111., a corporation of Ohio No Drawing. Filed Jan. 7, 1958, Ser. No. 707,466

Claims. (Cl. 208-263) This invention relates to a method of improving the physical properties of solvent extracts obtained during the manufacture of mineral lubricating oil fractions and relates, more particularly, to a method of reducing the neutralization number of solvent extracts by treatment with certain barium compounds.

In accordance with this invention, it has been foundthat the high-molecular-weight, acidic materials present in solvent extracts can be substantially, completely neutralized with solid barium oxide or barium hydroxide at temperatures ranging from about 250 to 400 F., and particularly about 350 F. It has been found that this reaction, involving as it does the high-molecular-weight acidic substituents in solvent extracts, proceeds to completion yielding a product having a low neutralization number on the order of 0.5 or less and that, contraryto the prior art, the various solid alkali metal oxides, hydroxides, or basic salts, and alkaline earth metal oxides, hydroxides, or basic salts are not equivalent to barium oxide or hydroxide for this purpose.

The acidic substituents that are expected and carried along into the extract phase of solvent extracts include the higher-molecular-Weight naphthenic acids along with other organic acids, inorganic acids, esters, phenolic compounds, lactones, petroleum resins, and certain salts of heavy metals. The greater portion of these acidic substituents, commonly referred to as naphthenic acids, are characterized as high-molecular-weight carboxylic acids. These substances are liquid and/or solid aliphatic acids and alicyclic acids having above about 25 carbon.

atoms to the molecule, showing little or no unsaturation and consisting essentially of cyclic acids and polycyclic In general, these acidic materials which are responsible for the acid nature of solvent extracts, have boiling ranges above about 600 F., and are the most difficult type of acidic materials to remove or counteract in heavy fractions of lubricating oils.

In the preparation of lubricating oils from crude. petroleum, it is the practice to subject both heavy and residual lubricating oil stocks to chemical and physical.

treatments in order to improve the viscosity characteristics, low-temperature fluidity, oxidation stability, and lower the carbon residue, sulfur content, and neutralization values in order that the requirements of modern lubrication may be met by the lubricating oils. One problem that has faced the refiner of lubricating oils is the removal of acidic constituents from the heavy or residual lubricating oil stocks, as, for example, preparing such lubricating oils with low acid numbers as determined by ASTM D974-52T. As the refining operations of dewaxing, deasphalting, and solvent refining exert their influence upon the lubricating oil fractions, the acidic constituents remaining become much more diflicult to remove. Refiners have in the past applied various solvent extraction methods employing dilute aqueous alkali solu tions and various organic solvents in their effort to pro-'. duce lubricating oils having acceptable neutralization values. Aqueous and anhydrous ammonia solutionshave been used, followed by alcohol extractions, to remove the deleterious naphthenic acids. Aqueous ammonia solutions in combination with emulsion breakers, such as methyl alcohol, ethyl alcohol, or acetone, have been applied in various continuous countercurrent extraction processes in an efiort to finish lubricating oils for use with various additives that have become necessary to meet' the extreme conditions in modern lubrication. In addition, the prior art has applied various other alkaline materialsin attempts to neutralize the acidic constituents with various degrees of success. In spite of the prior art efforts, in many instances the persistence of acidic constituents or naphthenic acids in finished lubricants, re-;

. sidual fractions and solvent extracts has proved detri-,

mental.

The primary object of this invention is to provide a' method for producing aromatic extracts, from the manufacture of mineral lubricating oils, which have low neutralization number. I

Another object of this invention is to provide a process for producing aromatic extracts having low neutralization numbers by reaction of the acidic constituents therein with solid barium oxide or barium hydroxide.

Another object of this invention is to provide a method of neutralizing the naphthenic acid content ofaromatic extracts, particularly extracts obtained using phenol, produced during the preparation of bright stocks and tneu tral oils.

A further object of this invention is to provide aromatic extracts which, because of their low neutralization number, qualify as rubber extenders, lubricant components, grease components, and other uses where low acidity is essential. I

These and other objects of the invention will be described or become apparent as the invention is developed herein.

The process of this invention is very simply carried out by treating the acid-containing aromatic extract with solid barium hydroxide or oxide, at a temperature between about 250" F. and the flash point of the extract. As will be illustrated herein by the examples, it has been found that these solid barium compounds exhibit a' greater ability to neutralize the particular acidic constituents present in solvent extracts than do other solid' neutralizing materials known to the art, including hydroxides, oxides, and carbonates of the alkali metals and" the other alkaline earth metals.

Although concentrated alkali solutions, such vas 30% caustic soda solution, sometimes may be effective in. reducing the neutralization number to a very low value, the use of such solutions presents operating difliculties because of unresolvable emulsions, and, even when some of the oil can be separated, the difiiculty of satisfactorily: distilling same because of the presence of retained water still exists. Aromatic extract oils actually have an appreciable solvency for water. Consequently, We have found that treating aromatic extract oils with solutions of alkaline inorganic materials cannot be accomplished to any practical extent, and that they must be treated with solid materials of this kind in the substantial absence of water. We then found that only barium oxide and/oi" hydroxide are uniquely effective. This is considered un-' expected because the remaining members of groups I and II are generally considered more reactive and are commonly used in the prior art to neutralize acidic constituents in lubricating oils or to prepare salts of relatively I pure naphthenic acids. Also, the barium compounds" enumerated have been found tobe the only solid con-if meant to include those modifications containing water of crystallization. The barium oxide or hydroxide is used in'the solid state in the amount theoretically required to neutralize the acid content of the solvent extract. Amounts greater than stoichiometric may be used, although excessive amounts are not necessary to the end result and only increase the cost of the process. Furthermore, the use of excessive amounts of barium oxide or hydroxide tends to form suspensions of finely-divided particles in the end product, which suspensions are not easily broken. Amounts less than stoichiometric leave, unwanted residual acidity. After the acids in the solvent extracts have been neutralized, the neutral product can be removed by simple distillation and the overhead is collected as a substantially neutral oil well suited for use as a component in lubricating oil fractions, as a rubber extender, or as a component in greases, The low-neutralization-number aromatic extract oil of this invention may be used in any application wherein the character of low acidity or-neutralization number is paramount.

In order to further demonstrate the invention, a number of examples are given.

EXAMPLE 1 To a 100 g. sample of phenolextract having a 1948 neut. number of 6.1, we added 1.4 g. (1.5 theory) of barium hydroxide. The mixture was then heated over a period of about twenty minutes to 350 F., with stirring. Reaction started at 250 F., with noticeable quantities of steam being evolved, and continued until heating was stopped at a temperature of 350 'F. The resulting prodnot had a 1948 neut. number of only 0.15. It is probable that the neut. number would have been reduced to zero had the reaction been allowed to proceed to completion. The product was clear, with no apparent color change.

EXAMPLE 2 e 1 To 1500 g. of phenol extract having a 1948 neut. No. of 17.2, from the production of 170/100 neutral oil was added 16.4 g. (1.17 theory) of barium hydroxide. The mixture was heated and stirredv as in Example 1. The resultant product had a 1948 neut. number of 0.59, again indicating that suflicient time had not been allowed for completion of thereaction. This product was then distilled at 3 mm. pressure (Hg absolute) with V. fractions being collected. Results of this distillation were as follows:

Table l For comparison, a series of experiments was conducted in which various solid treating agents were contacted with a phenol extract at substantially the same temperature for 60 minutes, or until a neutralization number of below.

about 0.6 was obtained, whichever occurred first. These experiments are reported in Table II.

Table II Temp Time, Final Run Threating Agent (T F.) min- Neut.

utes No.

1 Ba(OH) 350 20 0. 594 2 MgCOa 360 60 7. 2 3 MgC O +l%HzO 230 60 7. 2 4. NaOH* 350 60 3. 5 5 NaHOO 410 60 3.342 6 02001 e 360 60 7. 2

In these runs there was apparent reaction pbut the final product was much more acidic than that obtained using barium hydroxide.

did not result in a further lowering of the neutralization number. In contrast, these same treating agents, as used in experiments 2 through 6 of Table II, are capable of reducingthe neutralization number of ordinary lubricating fractions. It appears, therefore, that the naphthenic acids present in solvent extracts are particularly difiicult to neutralize with solid treating agents and barium oxide or hydroxide are specific for this reaction. The phenol extract used in the experiments in Table II is the same phenol extract as used in Example H, and has a 1948 neutralization number of 7.2.

Regarding the aromatic extract to be treated inaccordance with this invention, any solvent extract obtained from the treatment of lubricating oil fractions with a solvent'in the manufacture of neutral and bright stock lubricating oils,-may be used. These materials are well known in the art and, accordingly, only a brief descrip tion of their preparation is necessary.

. In a typical operation, desalted crude oil is first charged to a distillation unit where straight-run gasoline, two

grades of naphtha, kerosene, and distillate are taken off,'le aving a reduced cruderesidue. The reduced crude is continuously charged to 'a vacuum distillation unit Where three lubricating oil distillates are taken oil as side streams, a light distillate. is taken off as overhead, and a' residuum is withdrawn from the bottom of the tower. This residuum is charged to a propane dea'sphalting unit'wherein propane dissolves the desirable lubricating oil constituents and, leaves the asphaltic materials. A typical vacuum residuum charge to the propane deasphalting unit may have an API gravity of 12.9",

viscosity SUS at 210 F. of 1249, flash 585 F., fire 650 F., C.R. of 13.9 weight percent and is black in. color. Thedeasphalted oil may have an API gravity of 21.5 to 21.8, viscosity SUS at210 F. of -175, NPA color 6-7, flash 575 F., fire 640 F., and C.R. of The deasphalted oil and various lubricating oil distillates from the reduced crude are separately sub: jected' to solvent extraction for the separation of non aromatic from aromatic constituents. The refined oil or rafiinate from such processes is used as a blending stock and the solvent extract, containing the aromatic. constituents, is the material to be treated in accordance with this invention. a

For example, a Van Zandt crude oil with an API gravity of 33.1 was topped to remove such light fractions as gasoline, naphtha, kerosene, and a light lubricating distillate. The vacuum residue was a reduced crude having a viscosity of 1251 SUS at 210 F., 2.2 percent sulfur, and an API gravity of 12.6. After propane deasphaltillg,v the oil had a'viscosity of 174 SUS at 210 F. and an API gravity of 21.7. This deasphalted oil was treated with phenol to produce a rafiinate from which an aviation lubricating oil may be produced. The extract phase from this phenol treatment, after neutralization in accordance with this invention, is ready for use in preparing greases, lubricating compositions, rubber compositions, etc., where low acidity is required.

Solvents other than phenol may be used to obtain the extract oil used in accordance with this invention; for example, liquid sulfur dioxide, nitrobenzene, Chlorex, chlorophenol, trichloroethylene, cresylic acid, pyridine, furfural or the Duo-Sol solution (comprising liquid propane, phenol, and cresol) may be used. When using phenol, it is possible to vary the characteristics of the extract oil considerably by adjustment of the amount of water in the solvent. A low V.I. cut may be obtained by using a water solution of phenol during the extraction and a high V.I. cut may be obtained by using anhydrous phenol. Following are the physical characteristics of typical extract oils from lubricating oil stocks derived from various crude oils which may be used in accordance with this invention.

What is claimed is: p

l. The process for reducing the neutralization number of aromatic extract oils obtained from the manufacture of lubricating oils and containing acidic materials boiling above about 600 P. which comprises contacting said aromatic extracts with a solid substantially anhydrous barium compound selected from the group consisting of barium oxide and barium hydroxide, said barium compound being present in at least the amount stoichiochiometrically required to neutralize the acidic materials present in said extract oil, and recovering aromatic extract having a reduced neutralization number.

2. The process in accordance with claim 1 in which said barium salt is barium hydroxide.

3. The process in accordance with claim 1 in which said barium salt is barium oxide.

4. The process in accordance with claim 1 in which said aromatic extract is obtained from the manufacture of neutral oil.

Table III SOURCES AND PHYSICAL CHARACTERISTICS OF SOLVENT EXTRACTS Extract No. Crude Source Solvent AP I Sp. Gr. Via/100 Via/130 Gravity at 10 F. F.

Van Zandt 11. 1 4, 750 do 15. 4 -d0 12.6 4, 310 do 14. 6 4, 305 do. 15.4

am 13. 7 5, 400 do 8. 6 19, 000 do 10. 5 2, 514

Santa Fe Springs 10. 2 Tex s 13. 0 12.2 Nitro-B mPnP 10. 0 Propane-cresol- 14. 4 hen 13.6 Chlorex 13. 6 Phenol 8. 9 Furt'ural 14. 9

Phenol 13. 5 976 25, 000 do 17.6 157.3 81.3 ---.-d0- 10.8 1,327 397 F. Iodine Percent Pour Flash Fire No. C.R. Sulfur Table III shows the physical properties of extracts #19 and 20 which were used in Examples 1 and 2 and the results shown in Tables I and II. The extracts shown in Table III are merely illustrative and the invention is not to be limited thereby. It is to be understood that any extract oil obtained from the refining of mineral lubricating oil by solvent extraction wherein the purpose is to separate as the rafiinate phase the substantially nonaromatic hydrocarbons and as an extract phase the predominantly aromatic constituents, may be used. The solvent extracts are freed of solvent by stripping prior to their use so that they contain no solvent; for example, phenol extracts are dephenolized by steam stripping. These operations are well known in the prior art and further description is unnecessary.

5. The process in accordance with claim 1 in which said aromatic extract is obtained from the manufacture of bright stock oils.

6. The process in accordance with claim 1 in which said reaction is carried out at a temperature between about 250 F. and the flash point of the aromatic extract.

7. The process in accordance with claim 1 in which said reaction temperature is about 350 F.

8. The process in accordance with claim 1 in which said aromatic extract is a phenol extract having an initial neutralization number of 6.1 and the finished product has a neutralization number of 0.15.

9. The process in accordance with claim 1 in which said aromatic extract is a phenol-obtained extract having an initial neutralization number of 7.2 and the finished faroduct has a neutralization number of 0.59.

l :lOfThe process in accordance with claim 1 in which said aromatic-extract is obtained from the solvent extraction of lubricating oil fractions by treatment with a solvent selected from the group consisting of phenol, sulfur dioxide, nitrobenzene, furfural, and chlorophenol.

References Cited in the file of this patent NITED STATES PATENTS Moser s c- Jan. 7, 1941 Soday l.. July 22, 1941 Edwards et a1. Dec. 16, 1941 Ellender Oct. 12, 1948 Heid Nov. 23, 1948 Bowman Nov. 24, 1953 Holm et al. Aug. 5, 1958 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION May 31, 1960 Patent No 2 9383362 Weldon Go Annable et al.,

s in the printed specification It is hereby certified that error appear tion and that the said Letters of the above numbered patent requiring correc Patent should read as corrected below.

for expected read extracted to the second column for column 6, lines 9 and 10 d stoichiometrically Column 1, line 37 column 4. Table II heading "Threating" read Treating for "stoichiochiometrically rea Signed and sealed this 4th day of April 1961,

(SEAL) Attest: ERNEST W. SWIDER ARTHUR W. (ROCKER XMXKX XNX Acting Commissioner of Patents Attesting Oificer 

1. THE PROCESS FOR REDUCING THE NEUTRALIZATION NUMBER OF AROMATIC EXTRACT OILS OBTAINED FROM THE MANUFACTURE OF LUBRICATING OILS AND CONTAINING ACIDIC MATERIALS BOILING ABOVE ABOUT 600*F. WHICH COMPRISES CONTACTING SAID AROMATIC EXTRACTS WITH A SOLID SUBSTANTIALLY ANHYDROUS BARIUM COMPOUND SELECTED FROM THE GROUP CONSISTING OF BARIUM OXIDE AND BARIUM HYDROXIDE, SAID BARIUM COMPOUND BEING PRESENT IN AT LEAST THE AMOUNT STOICHIOCHIOMETRICALLY REQUIRED TO NEUTRALIZE THE ACIDIC MATERIALS PRESENT IN SAID EXTRACT OIL, AND RECOVERING AROMATIC EXTRACT HAVING A REDUCED NEUTRALIZATION NUMBER. 